Mercury rotary switch



April 23, 1963 M. A. Rl-:MKE

' MERCURY ROTARY SWITCH Filed Sept. 30, 1960 INVENTOR. M A. REMKE A TTORNEVS United States Patent O 3,087,036 MERCURY RQTARY SWITCH Marvin A. Reinke, Bartlesville, Gioia., assigner to Phillips Petroleum Company, a corporation of Delaware. Fiied Sept. 30, 1960, Sex'. No. 59,647 6 Claims. (Cl. 20G-152) This invention relates to an improved rotary switch employing mercury `as .a contact medium.

Electrical switches of various types, including those employing mercury las a Contact medium, have been in wide use. In particular applications of mercury switches, certain deficiencies have been noted. It has been observed that where a mercury contact pool is employed there is a failure to make electrical contact quickly and break electrical contact quickly. A present need exists for a mercury switch capable of making positive contact closure rapidly and without friction, overbalance or chatter.

Accordingly, an object of this invention is to provide an improved rotary mercury switch capable of making or breaking an electrical circuit rapidly.

Another object of this invention is to provide a rotary mercury switch -with yan improved method of adjusting the contact position of each of a plurality of electrical contacts.

Another object of this invention is to provide a rotary mercury switch with an improved method of simultanea ously making one electrical circuit and breaking a second electrical circuit. Y

Other objects, `advantages and feature-s of my invention will be readily apparent to those skilled in the tart from the following description and Aappended claims.

Broadly, the inventive rotary mercury switch consists of a chamber of glass or other non-conducting material -approximately half filled with mercury. A center post or other pivoting mechanism is provided about which the chamber rotates land two or more electrical contacts are spaced about the periphery of the chamber. The charnber Ithus becomes a rotary electrical switch in which at least one of the electrical contacts serving as a common electrode is in constant contact with the body of mercury as the entire assembly is rotated. The contacts can be provided with non-conducting end caps which operate to make or break the electrical circuit rapidly upon immersion or Withdrawal from the mercury pool. Thus, quickmaking, quick-breaking is achieved, even with slow rotation, and arcing is minimized.

FIGURE l is an exploded view of a preferred form of the inventive rotary mercury switch.

FIGURE 2 is a partial cutaway front View of one of the mercury chambers of FIGURE 1.

FIGURE 3 is a side view of a mercury chamber support of FIGURE l.

FIGURE 4 is a cross-sectional view of another embodiment of the inventive rotary mercury switch taken along the lines 4-4 of FIGURE 5.

FIGURE 5 is a cross-sectional view of FIGURE 4 taken along the lines 5 5.

FIGURE 6 is an enlarged view of an electrical contact with `a non-conducting end cap.

Referring to the drawing, FIGURE 1 illustrates three Amercury chambers (10, 11 and 12) independently friction- .fmounted upon support members 14, 15 and 16, respective- ICC ly, so as to hold said mercury chambers in fixed relationship to said support members. Mercury chamber snpport members 14, 15 and 16 are positioned on `shaft 17 in fixed relationship to each other by means of gaskets 1S and `are friction-mounted upon shaft 17 so that in operation a rotation of shaft 17 will impart Aan identical rotation to mercury chambers 10, 11 and 12.. Mercury chambers 11i, 11 and 12 can be independently rotated about their respective support members so as to adjust the position of said mercury chambers with respect to shaft 17. Shaft 17 is Aattached to a plate 19. Plate 19 can be attached, for example, to a conventional recorder so as to operate directly off `the pivot point of the recorder and so rotate with the rotary motion of the indicating arm of said recorder. Thus, as the recorder indicating arm rotates in its arc, the switch also rotates through an identical arc.

Reference is made to FIGURE 2, where mercury chamber 10 of FIGURE l is illustrated in detail. As shown,

'mercury chamber 1t) is fabricated from glass tubing or other suitable non-conductive material so fas to provide a sealed chamber with a means 20, ysuch 4as 4the place where the glass tubing is sealed, of manually adjusting the position of the chamber 10 with respect to shaft 17. It is, of course, within the scope of this invention to provide other means of manually rotating chamber 10 about shaft 17. Chamber 1t) is substantially half filled with mercury 21 with the upper region of chamber 1li filled with hydrogen at a pressure of lapproximately 1A; atmosphere. The use of hydrogen at a reduced pressure in the preparation of mercury switches is well known in the art. Electrical contact electrodes 22 Iand 23 extend within chamber 10 and the ends of said electrodes are preferably capped with a non-insulating material, such as glass. End caps 24 and 25, respectively, are preferably substantially spherical in shape, but not necessarily limited thereto, with that portion of each end cap sphere attached to each contact electrode fabricated so as to provide a plane 46 (FIGURE 6) parallel to the surface of the body of mercury at the lposition wherein contact ybetween said end cap and said body of mercury is made or broken. The contact electrode is preferentially attached to the center portion of the `parallel plane. Common electrodes 26 and 26 are positioned apart so that for any position of rotation at least one of the common electrodes is lin contact with the body of mercury. Additional electrical contact electrodes can be positioned throughout chamber 10 and, as previously disclosed, it is Within the scope of this invention to provide a mercury chamber having only one contact electrode in addition to the previously described common electrode.

A means of supporting mercury chamber 1t) about shaft 17 is illustrated by FIGURE 3. Support member 14 is friction mounted upon shaft 17, rotating in the same manner as shaft 17. Rotation is thereby directly imparted to mercury chamber 10.

FIGURE 4 illustrates another form of the rotary mercury switch. A mercury chamber is formed by -a back plate Si), adjustable rotatable wafers 27, 28 and 29, and a bolted face plate 31. As wafers 27, 28 and Z9 must be capable of being independently rotated about shaft 32, the mercury chamber is fabricated from .a material such as plastic, permitting wafers 27, 28 and 29 to be independently rotated and at the same time maintaining a sealed mercury chamber. A means of rotating the wafers is illustrated in FIGURE 5, wherein a rotating Iarm 34 is attached to wafer 27. A common electrode 33 is attached to shaft 32 `so that for any rotation of wafer 27 within an arc of 180 common electrode 33 will remain in contact with the body of mercury 3S. It is, of course, to be understood that should it be desirable to adjust wafer 27 so as to be operable within a rotation arc of 360, common electrode 33 can be `so positioned so as to remain in constant contact with the body of mercury 3S through a lrotation of 360. Electrical contact electrodes 36 and 37 with non-conducting insulating end caps 38 and 39, respectively, are positioned so as to be immersed in the body of mercury 35 at certain positions of rotation of the mercury chamber and at other positions of rotation said electrical contact electrodes 36 and 37 will be out of contact with lthe body of mercury.

The operation of the rotary mercury switch will be discussed as it applies to the form illustrated in FIGURES l and 2. The operational principles are equally applicable to the form illustrated by FIGURES 4 and 5. Electrical contact electrodes 22 and 23 are attached to separate electrical circuits, both electrical circuits having a common electrode 26. In the present position illustrated by FIG- URE 2, the body of mercury 21 is bridging the gap between contact electrode 22 and common electrode 26, thus completing or closing the electrical circuit. As the mercury is not in Contact with contact electrode 23, only non-conducting end cap 25, the circuit containing electrode 23 is open. FIGURE 2 illustrates the utilization of the surface tension of mercury to provide a switch having a qui k-make and a quick-break. As shown, it can be considered that mercury chamber is in the process of being rotated clockwise. As contact electrode 22 moves upward, the surface tension exerted upon end cap 24 will cause the contact electrode 22 to lose contact quickly with the mercury, giving a unique snap action effect in breaking the electrical circuit. At the same time, the mercury surface tension acted upon by insulating end cap 25 will cause contact to be made between the body of mercury 21 and contact electrode 23 with the previously described snapping effect. By providing spherical end caps wit-h parallel planes in the heretofore described manner, contact between the body of mercury and the contact electrodes is evenly made `and broken with arcing reduced to a minimum. As contact between the contact electrodes and the mercury is instantly completed and instantly broken, arcing is minimized. It is preferred that the contact electrodes 22 and 23 be positioned so as to enter and leave the body of mercury 21 perpendicular to the surface of said body of mercury 21 to thus insure a quick-make and a quick-break. With mercury chamber 10 having two common electrodes 26 and 26', contact electrodes can so be positioned that throughout 360 of rotation a circuit can be made and/ or broken.

Contact electrodes 22. and 23 can be so positioned that as the circuit containing electrode 22 is broken, the circuit containing electrode 23 is simultaneously closed. There is no time lag. The utilization of this important feature is particularly adapted to those situations wherein one operation must be automatically commenced instantly upon the completion of a second operation. It is, of course, obvious that electrical contacts can be placed at any desired spacing and it is not necessary that one circuit be completed at the same time another is broken.

Two or more mercury chambers, each containing two or more electrodes, can be combined in the manner illustrated by FIGURE 1. Each of mercury chambers 10, 11 and 12 are rotatably positioned about shaft 17 independent of the other mercury chambers. A rotating motion imparted to shaft 17 causes mercury chambers 10, 11 and 12 to rotate in a like manner This rotation causes electrical circuits to be broken or closed in the heretofore described manner.

The rotary switch of FIGURE 1 can be attached directly to a conventional tank level recorder so as to operate directly off the pivot point of the recorder. 'Ihe mercury switch will then rotate with the rotary motion of the indicating arm. As the level indicating arm rotates through its given arc, the switch als-o rotates through the same arc. The switch can t-hus be used to open valves, close valves or start pumps in response to a recorded tank level. The rotary switch creates no noticeable drag or additional hysteresis to the level indicator as there is no additional friction in the action of the switch and no overbalancing effect of the mercury. The unique snap action eiect on contact opening and closing is obtained by utilization of mercury surface tension in the aforementioned described manner.

As is evident to those skilled in lthe art, other forms of the rotary switch illustrated in FIGURES 4 yand 5 can be utilized in a similar manner.

As will be evident to those skilled in the art, other modifications of this invention can be made, or followed, inthe light of the foregoing disclosure and discussion, without departing from the spirit or scope thereof.

I claim:

1. A rotary mercury switch comprising an annular insulated rotatable mercury chamber with a horizontal axis of rotation, said chamber containing a body of mercury substantially lling a portion of said mercury chamber; a plurality of contact electrodes extending into the interior of said mercury chamber, -said contact electrodes being circumferentially spaced from each other so that each of said contact electrodes can be immersed in said body of mercury in certain positions of rotation of said chamber and each of said contact electrodes can be out of contact with said body of mercury in other positions of rotation of `said chamber; said contact electrodes provided with non-conducting substantially spherical-shaped end caps, each of said end caps being the rst portion of each of said contact electrodes to make contact with said body of mercury upon rotation of said mercury chamber and the last portion of each of said contact electrodes to break Y contact with said body of mercury; and at least one common electrode constantly immersed in -said body of mercury.

2. The rotary mercury switch of claim 1 wherein said contact electrodes are circumferentially and axially spaced about and along, respectively, said horizontal axis, the position of each of said axially spaced contact electrodes independently adjustable with respect to said body of mercury.

3. A rotary mercury switch comprising an annular insulated rotatable mercury chamber with a horizontal axis of rotation, said chamber containing a body of mercury filling a portion of said mercury chamber; at least one contact electrode extending into the interior of said mercury chamber so that said contact electrode can be immersed in said body of mercury in certain positions of rotation of said chamber and said contact electrode can be out of contact with said body of mercury in other positions of rotation of said chamber; each contact electrode provided with a non-conducting end cap substantially spherical in shape, each end cap being the rst portion of each said contact electrode to make contact with said body `of mercury upon rotation of said mercury chamber and the last portion of each of .said contact electrode to make contact with said body of mercury; and at least one common electrode constantly immersed in said body of mercury.

4. The rotary mercury switch of claim 3 wherein each substantially spherical non-conducting end cap is fabricated so as to provide a plane parallel to the surface of said body of mercury at the positions wherein contact between said contact electrode and said body of mercury is made and broken, Isaid contact electrode yattached to said end cap at the center of said parallel plane.

5. A rotary mercury switch comprising an annular insulated rotatable mercury chamber with a horizontal axis of rotation, said chamber containing a body of mercury substantially filling the lower half of said mercury chamber; pairs of contact electrodes axially spaced along said horizontal axis and extending into the interior of said mercury chamber, the position of each of said pairs of axially spaced contact electrodes independently adjustable with respect to said Ibody of mercury, the rst member of each of said pairs circumferentially spaced from the second member of each of said pairs so that when in certain positions of rotation of said chambers said rst member is immersed in said body of mercury and said second member is out of contact with said body of mercury, said rst Iand second members simultaneously interchanging positions with respect to said mercury contact upon rotation of said mercury chamber, each of said contact electrodes provided with a non-conducting end cap substantially spherical in shape, each said end cap being the rst portion of each said contact electrode to be in contact with said tbody of mercury upon rotation of said mercury chamber and the last portion of each of said contact electrode to break contact with said body of mercury; and `at least one common electrode constantly immersed in said body of mercury.

6i. The rotary mercury switch of claim 5 wherein each substantially spherical-shaped non-conducting end cap is fabricated so as to provide a plane Vparallel to the surface of said body of mercury at the positions wherein contact between said Contact electrode and said body of mercury is made and broken, said contact electrode attached to said end `cap at the center of said parallel plane.

Butler Feb. 6, 1912 Corliss Mar. 22, 1949 

1. A ROTARY MERCURY SWITCH COMPRISING AN ANNULAR INSULATED ROTATABLE MERCURY CHAMBER WITH A HORIZONTAL AXIS OF ROTATION, SAID CHAMBER CONTAINING A BODY OF MERCURY SUBSTANTIALLY FILLING A PORTION OF SAID MERCURY CHAMBER; A PLURALITY OF CONTACT ELECTRODES EXTENDING INTO THE INTERIOR OF SAID MERCURY CHAMBER, SAID CONTACT ELECTRODES BEING CIRCUMFERENTIALLY SPACED FROM EACH OTHER SO THAT EACH OF SAID CONTACT ELECTRODES CAN BE IMMERSED IN SAID BODY OF MERCURY IN CERTAIN POSITIONS OF ROTATION OF SAID CHAMBER AND EACH OF SAID CONTACT ELECTRODES CAN BE OUT OF CONTACT WITH SAID BODY OF MERCURY IN OTHER POSITIONS OF ROTATION OF SAID CHAMBER; SAID CONTACT ELECTRODES PROVIDED WITH NON-CONDUCTING SUBSTANTIALLY SPHERICAL-SHAPED END CAPS, EACH OF SAID END CAPS BEING THE FIRST PORTION OF EACH OF SAID CONTACT ELECTRODES TO MAKE CONTACT WITH SAID BODY OF MERCURY UPON ROTATION OF SAID MERCURY CHAMBER AND THE LAST PORTION OF EACH OF SAID CONTACT ELECTRODES TO BREAK CONTACT WITH SAID BODY OF MERCURY; AND AT LEAST ONE COMMON ELECTRODE CONSTANTLY IMMERSED IN SAID BODY OF MERCURY. 